MINES AND MACHINERY. 399 



any other given weight of coal consumed in working a 

 steam engine ; since the quantity of water that the engine 

 will raise to a given height, or the number of quarters of 

 corn that it will grind, or, in short, the amount of any other 

 description of work that it will do, is proportionate to that 

 duty. As the principal working of mineral veins can only 

 be continued by descending deeper every year, the diffi- 

 culty of extracting metals is continually on the increase, 

 and can only be overcome by those enlarged powers of drain- 

 over matter has been increased seventeen fold since the first invention of 

 these engines; and increased nearly tlireefold within twenty years. 



There is now an engine at the mines called the Fowey Consols in Corn- 

 wall, of which Mr. Taylor considers the average duty, under ordinary 

 circumstances, to be above 9,000,000; and which has been made to lift 

 97,000,000 lbs. of water one foot high, with one bushel of coals. 



The effect of these improvements on the operations of mines, in facilitating 

 their drainage, has been of inestimable importance in extracting metals from 

 depths which otherwise could never have been reached. Mines which 

 had been stopped from want of power, have been reopened, others have 

 been materially deepened, and a mass of mineral treasure has been ren- 

 dered available, which without these engines must have been for ever inac- 

 cessible. 



It results from these rapid advances in the application of coal to the pro- 

 duction of power, and consequently of wealth, that mining operations of vast 

 importance, have been conducted in Cornwall at depths till lately without 

 example, e. g. in Wheal Abraham, at 242 fathoms, at Dolcoath at 2.35 fa- 

 thoms, and in the Consolidated Mines in Gwennap at 290 fathoms, the latter 

 mines giving daily employment to no less than 2,500 persons. 



In the Consolidated Mines, the power of nine steam engines, four of which 

 are the largest ever made, having cylinders ninety inches in diameter, lifts 

 from thirty to fifty hogsheads of water per minute, (varying according to 

 the season) from an average depth of 230 fathoms. The produce of these 

 mines has lately amounted to more than 20,000 tons of ore per annum, 

 yielding about 2,000 tons of fine copper, being more than one-seventh of the 

 whole quantity raised in Britain. Tiie levels or galleries in these mines ex- 

 tend in horizontal distance a length of about 43 miles. (See J. Taylor's 

 account of the deptiis of mines, third report of British Association, 1833, p. 

 428.) 



Mr. J. Taylor farther states, (Lond.' Edin. Phil. Mag. Jan. 1836, p. 67) 

 that the steam engines now at work in draining the mines in Cornwall, are 

 equal in power to at least 44,000 horses, one-sixteenth part of a bushel of 

 coals performing the work of a horse. 



